1. Field of the Invention
Aspects of the present invention relate to a lithium secondary battery. More particularly, aspects of the present invention relate to a lithium secondary battery with a supporting sealing member between a safety vent and a gasket to enhance safety of the lithium secondary battery by reducing or preventing a gas or an electrolyte from leaking from the lithium secondary battery.
2. Description of the Related Art
Lithium secondary batteries may be classified as a cylindrical lithium secondary battery and a rectangular lithium secondary battery according to an exterior shape. The cylindrical lithium secondary battery has a built-in current limiting structure in a cap assembly to stop a current generating reaction when an internal pressure of the battery is raised above a certain limit and when there is a risk of explosion. Accordingly, the structure enhances the safety of the lithium secondary battery.
The cylindrical lithium secondary battery 10, as shown in FIG. 7, is composed of an electrode assembly (not shown) in the interior, a cylindrical can 30 that receives the electrode assembly and an electrolyte, and a cap assembly 40 that is assembled in the upper side of the cylindrical can 30 and seals the cylindrical can 30 to divert the current generated from the electrode assembly to an external device.
The related art cap assembly 40 is configured to have the following elements be sequentially inserted into the cylindrical can 30. The elements include a gasket, a safety vent, a current isolation member, a secondary protective element, and a cap up. Once each element is inserted into the cylindrical can 30 in the order discussed above, a rim of the cylindrical can 30 is crimped to keep the elements in place and prevent the gas and the electrolyte from leaking. However, with only this configuration, there is a risk of separation between the safety vent and the gasket and a risk of leakage when the internal pressure of the battery 10 is raised since a complete seal is not formed. Also, if the electrolyte flows into a slight gap between the cap assembly 40 and the gasket or between the gasket and the cylindrical can 30, due to an impact, a jolt, etc., there is a risk of electrolyte leakage out of the battery by interaction of a capillary phenomenon and a cohesive power of the electrolyte, etc.